1. Field
The described technology relates generally to a laser sealing device and a manufacturing method of an organic light emitting diode (OLED) display using the same.
2. Description of Related Art
An organic light emitting diode (OLED) display includes two electrodes and an organic light emitting element including an organic emission layer located between the two electrodes, wherein electrons injected from one electrode and holes injected from the other electrode are combined on the organic emission layer to form excitons that emit light while emitting energy.
The OLED display includes an element substrate formed with at least one organic light emitting element, an encapsulation substrate combined to the element substrate to encapsulate the organic light emitting element, and a frit to combine the element substrate and the encapsulation substrate.
If the element substrate is large, a frit having a wide width is used, which may require a uniform or near uniform temperature to melt the frit via a laser beam. If the temperature at which the frit is melted is not uniform, bubbles may be generated in areas where the temperature in the frit is higher, and/or an underlying metal wire may be damaged.
Accordingly, energy density of a center portion of the laser beam is decreased using a laser mask to achieve uniform temperature of the frit. However, the energy density of the center portion of the laser beam might not be easily decreased because of the high energy density at a periphery of the laser beam.
Also, for the uniform temperature of the frit, when the energy distribution of a circular flat top laser beam is changed from a Gaussian shape to a flat shape (the laser beam having a diameter that is larger than the width of the frit), the energy density in the laser beam irradiated to the frit center portion is larger than the energy density of the laser beam irradiated to the frit peripheral portion, such that the temperature of the frit center portion is higher than the temperature of the frit peripheral portion. In this case, the temperature of the center portion of the frit is increased such that bubbles may be generated, and when a metal wire is disposed under the frit, the metal wire might be expanded upward, or bulged, and the frit may be damaged.
Also, when using a quadrangle flat top laser beam to remove an imbalance of an incident energy density of the circular flat top laser beam, the energy in the frit peripheral portion, as compared with the frit center portion, is largely lost due to an edge effect, such that the temperature of the frit center portion is still high and the temperature of the frit is non-uniform. In this case, if the energy of the laser beam irradiated to the frit peripheral portion is increased to seal the frit peripheral portion, the metal wire might be damaged, and bubbles might be generated in the frit center portion, such that a micro crack may be generated.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the described technology, and may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.